Book  (Oct 2001)  Page(s) 314.  Includes photo(s).

Book  (1999)  Page(s) 237.  
 
...azure blue with a rosy flush at the base of the midrib.

Book  (1999)  Page(s) 131.  
 
Clematis 'Perle d'Azur', cv. (France), 1952

Book  (1995)  Page(s) 63.  
 
the most spectacular use of clematis in the whole garden is the planting of five 'Perle d'Azur' on the arc of the Powys Wall... The clematis are cut back hard in late autumn each year, and every ten days or so during May and June they are spread out across the wall and tied in...

Website/Catalog  (1963)  Page(s) 53.  
 
Perle d'Azur, bleu ciel.

Magazine  (28 Jul 1937)  Page(s) 56.  
 
Other beautiful varieties not yet available here [in the U.S.] are W. E. Gladstone (lilac), Otto Froebel (gray with a lovely flush), Perle d'Azur (light blue), blooming on new wood, and La Lorraine (pink suffused with lavender) and Edouard Desfossé (violet with deeper bars), blooming on old wood.

Magazine  (Jul 1937)  Page(s) 106.  
 
Quoi qu’il en soit en horticulture, le nom de C. Hakonensis ne servit pas couramment, on conserva celui de C. Jackmani. Par des semis et des croisements heureux : Morel, de Lyon, obtint Etoile violette, François Morel, Perle d'azur, Ville de Lyon.

Website/Catalog  (1935)  Page(s) 24.  
 
Perle d'azur.- Bleu ciel.

Website/Catalog  (1932)  Page(s) 24.  
 
Clématites à grandes fleurs....Perle d'Azur. Bleu ciel.

Website/Catalog  (1924)  Page(s) 107.  
 
Perle d'azur (Jackmani). Nombreuses fleurs bleu de ciel.